Apparatus for moving shift rail of transmission

ABSTRACT

An apparatus for moving a shift rail of a transmission may include a control shaft provided to be moved in a direction perpendicular to a plurality of shift rails by an actuator, a plurality of rollers protruding from one selected among a corresponding one of the shift rails and the control shaft, the rollers being formed on one of facing sides of the shift rail and the control shaft, and a cam protruding in an S-shaped form from a remaining one selected among the corresponding shift rail and the control shaft, on which no roller is formed, the cam being provided to selectively move the shift rails in an axial direction by moving while coming into contact at opposite sides thereof with the rollers depending on a distance by which the control shaft is moved.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a Divisional of U.S. patent application Ser.No. 15/367,073, filed Dec. 1, 2016, which claims priority to KoreanPatent Application No. 10-2016-0137942, filed on Oct. 21, 2016, in theKorean Intellectual Property Office, the entire contents of which isincorporated herein for all purposes by this reference.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to an apparatus for moving a shift rail ofa transmission, which may perform shifting and selecting operations viaa single actuator.

Description of Related art

Recently, a high-efficiency engine, a high-efficiency transmission, alightweight vehicle chassis, and the like have actively been studied toincrease the fuel efficiency of vehicles. In particular, in thetransmission field, the development of an automated manual transmission,which combines the high efficiency of a manual transmission with theconvenience of an automatic transmission, is being actively conducted.

In such an automated manual transmission, gear shifting is automaticallyachieved by a gear actuator without the involvement of a driver. Thatis, in order to realize the high efficiency of a manual transmission, ingeneral, shifting and selecting operations are performed by respectiveactuators so as to realize gear shifting.

Here, the automated manual transmission (AMT) requires two actuators forselecting and shifting operations, whereas a dual clutch transmission(DCT) requires four actuators for preliminary engagement. However,because price and power consumption increase along with the number ofactuators, it has conventionally been required to reduce the number ofactuators if possible.

The information disclosed in this Background of the Invention section isonly for enhancement of understanding of the general background of theinvention and should not be taken as an acknowledgement or any form ofsuggestion that this information forms the prior art already known to aperson skilled in the art.

BRIEF SUMMARY

Various aspects of the present invention are directed to providing anapparatus for moving a shift rail of a transmission, which may performshifting and selecting operations of the transmission using a singleactuator through the use of an S-shaped cam.

In accordance with an aspect of the present invention, the above andother objects can be accomplished by the provision of an apparatus formoving a shift rail of a transmission, the apparatus including a controlshaft provided to be moved in a direction perpendicular to a pluralityof shift rails by an actuator, a plurality of rollers protruding fromone selected among a corresponding one of the shift rails and thecontrol shaft, the rollers being formed on one of facing sides of theshift rail and the control shaft, and a cam protruding in an S-shapedform from a remaining one selected among the corresponding shift railand the control shaft, on which no roller is formed, the cam beingprovided to selectively move the shift rails in an axial direction bymoving while coming into contact at opposite sides thereof with therollers depending on a distance by which the control shaft is moved.

The rollers may be formed on a corresponding one of the shift rails tobe arranged side by side in the axial direction, and the cam may beformed in an S-shaped form in the axial direction along a center axis ofthe control shaft and is provided to pass across a gap between therollers formed on each shift rail.

The cam may be shorter than a distance between adjacent different shiftrails.

The shift rails may be moved to one side when one side of the cam comesinto contact with the rollers and may be moved to an opposite side whena remaining side of the cam comes into contact with the rollers, whilethe control shaft is moved.

The rollers may be arranged side by side in a radial direction on thecontrol shaft, and the cam may be formed in an S-shaped form in theradial direction on each of the shift rails and may be provided to allowthe rollers to surround and pass the cam, while the control shaft ismoved.

The cam may have opposite end portions having a curved shape.

The cam may be provided to continuously come into contact at oppositesides thereof with different rollers when moving between the rollers.

The methods and apparatuses of the present invention have other featuresand advantages which will be apparent from or are set forth in moredetail in the accompanying drawings, which are incorporated herein, andthe following Detailed Description, which together serve to explaincertain principles of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view illustrating an apparatus for moving ashift rail of a transmission according to various exemplary embodimentsof the present invention;

FIG. 2 is a view illustrating a cam an exemplary embodiment according toan exemplary embodiment of the present invention;

FIG. 3 is a perspective view illustrating an apparatus for moving ashift rail of a transmission according to various exemplary embodimentsof the present invention; and

FIG. 4, FIG. 5, FIG. 6, FIG. 7, FIG. 8, and FIG. 9 are viewsschematically illustrating an operation of the apparatus for moving theshift rail of the transmission according to an exemplary embodiment ofthe present invention.

It should be understood that the appended drawings are not necessarilyto scale, presenting a somewhat simplified representation of variousfeatures illustrative of the basic principles of the invention. Thespecific design features of the present invention as disclosed herein,including, for example, specific dimensions, orientations, locations,and shapes will be determined in part by the particular intendedapplication and use environment.

In the figures, reference numbers refer to the same or equivalent partsof the present invention throughout the several figures of the drawing.

DETAILED DESCRIPTION

Reference will now be made in detail to various embodiments of thepresent invention(s), examples of which are illustrated in theaccompanying drawings and described below. While the invention(s) willbe described in conjunction with exemplary embodiments, it will beunderstood that the present description is not intended to limit theinvention(s) to those exemplary embodiments. On the contrary, theinvention(s) is/are intended to cover not only the exemplaryembodiments, but also various alternatives, modifications, equivalentsand other embodiments, which may be included within the spirit and scopeof the invention as defined by the appended claims.

Hereinafter, an apparatus for moving a shift rail of a transmissionaccording to an exemplary embodiment of the present invention will bedescribed with reference to the accompanying drawings.

FIG. 1 is a perspective view illustrating an apparatus for moving ashift rail of a transmission according to various exemplary embodimentsof the present invention, and FIG. 2 is a view illustrating a cam anexemplary embodiment according to an exemplary embodiment of the presentinvention. Referring to FIG.1 and FIG. 2, the apparatus for moving ashift rail of a transmission may include a control shaft 10, which isprovided to be moved in a direction perpendicular to a plurality ofshift rails 20 by an actuator, a plurality of rollers 30, each of whichprotrudes from one selected among a corresponding shift rail 20 and thecontrol shaft 10, the rollers 30 being formed on one of facing sides ofthe shift rail 20 and the control shaft 10, and a cam 40, whichprotrudes in an S-shaped form from the other one selected among thecorresponding shift rail 20 and the control shaft 10, on which no roller30 is formed, the cam 40 being configured to selectively move the shiftrails 20 in the axial direction by moving while coming into contact, atopposite sides thereof, with the rollers 30 depending on the distance bywhich the control shaft 10 is moved.

Conventionally, a finger is formed on a control shaft to rotate alongwith the control shaft, and shift lugs are formed on plural shift rails,which correspond to the control shaft. Accordingly, gear shifting isperformed via movement of the shift rails when the finger is introducedbetween the shift lugs to rotate.

The conventional configuration described above requires two actuators,one of which rotates the control shaft to perform a shifting operationand the other one of which moves the control shaft in the axialdirection to perform a selecting operation so that the fingercorresponds to one of the shift rails.

In contrast, according to the technology disclosed herein, as a resultof providing the cam 40, having an S-shaped form, on one of the controlshaft 10 and the shift rail 20 and providing the rollers 30 on the otherone so that the cam 40 moves across the gap between the rollers 30, theshift rails 20, which are arranged side by side, may be shifted by asingle actuator.

Here, because the operation of shifting the shift rails 20 is possibleusing only a single actuator that moves the cam 40, no selectingoperation is necessary, which may reduce the number of actuators,compared to the conventional configuration.

The various exemplary embodiments of the disclosed technology has thefeature by which the rollers 30 are formed on each of the shift rails 20to be arranged side by side in the axial direction, and the cam 40 hasan S-shaped form in the axial direction along the center axis of thecontrol shaft 10 to pass across the gap between the rollers 30 formed onthe shift rails 20.

As illustrated in FIG.1 and FIG. 2, in the various exemplaryembodiments, the rollers 30 are formed on the shift rails 20, and thecam 40 is formed on the control shaft 10.

The rollers 30 are formed on the shift rails 20, which are arranged sideby side, in the axial direction of the shift rails 20 to protrudeupward, and the cam 40 is formed on the control shaft 10, which islocated at the upper side of the shift rails 20, at a positioncorresponding to the rollers 30 to protrude downward.

Accordingly, when the control shaft 10 is moved in the axial direction,the cam 40 is moved along with the control shaft 10 and passes throughthe gap between the rollers 30 formed on one of the shift rails 20 whilebeing in contact with the rollers 30. Accordingly, the cam 40selectively moves one of the shift rails 20 in the shifting direction.

When the control shaft 10 is moved, the shift rails 20 are moved to oneside when one side of the cam 40 comes into contact with the rollers 30,and are moved to the opposite side when the other side of the cam 40comes into contact with the rollers 30.

In addition, the cam 40 may be characterized by being shorter than thedistance between the adjacent shift rails 20.

Generally, when two or more shifting gears are simultaneously coupled bya single actuator, a desired transmission gear ratio may not be realizedand a breakdown may occur due to shifting shock.

In the disclosed technology, assuming that the length of the cam 40 isgreater than the distance between the shaft rails 20, the shift rails 20may be simultaneously shifted due to the shape of the cam 40, thuscausing the coupling of a plurality of shifting gears. Therefore, thelength of the cam 40 may be limited to ensure the coupling of only asingle shifting gear via the movement of the single cam 40.

In addition, opposite end portions of the cam 40 may be curved.Accordingly, when opposite end portions of the cam 40 are introducedinto the gap between the rollers 30, the phenomenon in which the endportions are caught by the rollers 30 may be prevented.

Various exemplary embodiments may have the feature by which the rollers30 may be arranged side by side in the radial direction on the controlshaft 10, and the cam 40 may be formed in an S-shaped form in the radialdirection on each of the shift rails 20, so that the rollers 30 surroundand pass the cams 40 when the control shaft 10 is moved.

FIG. 3 is a perspective view illustrating an apparatus for moving ashift rail of a transmission according to the various exemplaryembodiments of the present invention. As illustrated in FIG. 3, in thevarious exemplary embodiments, unlike the various exemplary embodiments,cams 40 having an S-shaped form may be provided on the shift rails 20,and rollers 30 may be formed on the control shaft 10.

FIG.4, FIG. 5, FIG. 6, FIG. 7, FIG. 8, and FIG. 9 are viewsschematically illustrating an operation of the apparatus for moving theshift rail of the transmission according to an exemplary embodiment ofthe present invention. Here, FIG. 4, FIG. 5, FIG. 6, FIG. 7, FIG. 8, andFIG. 9 will be described below based on the various exemplaryembodiments, in which the rollers 30 are formed on the shift rails 20and the cam 40 is formed on the control shaft 10.

For example, in a case of an AMT vehicle, one of the two shift rails 20may be a shift rail for synchronizing a reverse gear and a first gear,and the other one may be a shift rail for synchronizing a second gearand a third gear.

FIG. 4 illustrates the case where a shift lever is in the neutral rangeor the parking range, in which state the middle portion of the cam 40may be located between the rollers 30 of the shift rail 20, whichsynchronizes a reverse gear and a first gear. That is, when the middleportion of the S-shaped cam 40 is located between the rollers 30, thecam 40 does not move the shift rail 20, realizing the neutral state.

When the shift lever is manipulated to the reverse range for thebackward movement of a vehicle, as illustrated in FIG. 5, the cam 40 ismoved downward via the rotation of the control shaft 10, leading thecoupling of a reverse gear via the movement of the shift rail 20.

Conversely, when the shift lever is manipulated to the driving range forthe forward movement of a vehicle, as illustrated in FIG. 6, the cam 40is moved upward via the rotation of the control shaft 10. This may leadthe coupling of a first gear via the movement of the shift rail 20,allowing the vehicle to perform first-gear driving.

In addition, the other shift rail 20 is provided for the coupling ofsecond and third gears. When shifting is performed from a first gear toa second gear according to a vehicle speed and an APS map, asillustrated in FIGS. 7 and 8, the cam 40 is moved upward to move theother shift rail 20, realizing the coupling of the second gear.

Thereafter, when shifting to a third gear is performed, as illustratedin FIG. 9, the cam 40 is moved further upward to implement the couplingof the third gear via the movement of the shift rail 20.

However, this is merely one exemplary embodiment for facilitatingunderstanding, and the combination of shifting gears that may be coupledvia the shift rails 20 may be changed depending on the vehicle,transmission or designer, and may not be limited to a specificcombination.

For example, in the case of a Dual Clutch Transmission (DCT) including aplurality of transmission clutches, two actuators including an odd-gearactuator and an even-gear actuator may be provided to reduce the timetaken for shifting via preliminary engagement, which is an advantage ofthe DCT.

That is, a control shaft operated by the odd-gear actuator is providedto interact with a shift rail that couples first and third gears, orfifth and seventh gears, and a control shaft operated by the even-gearactuator is provided to interact with a shift rail that couples areverse gear and a second gear, or fourth and sixth gears.

Accordingly, although four actuators are required to realize aconventional DCT, according to the technology disclosed herein, a DCTmay be realized using two actuators. This reduction in the number ofactuators may reduce the price, weight and power consumption of thevehicle, resulting in improved vehicle marketability.

In addition, the cam 40 may be characterized in that it continuouslycomes into contact at opposite sides thereof with different rollers 30when moving between the rollers 30.

To this end, because the cam 40 has an S-shaped form, the thickness ofthe cam 40 may vary, as illustrated in FIGS. 2 to 9. That is, aninclined portion of the S-shaped cam 40 may be thin, and a bent portionof the S-shaped cam 40 may be thick. Accordingly, when the cam 40 ismoved between the rollers 30 such that opposite sides thereof arecontinuously in contact with the rollers 30, the control shaft 10 andthe shift rail 20 may be more stably moved.

As is apparent from the above description, in an apparatus for moving ashift rail of a transmission having the configuration described above,shifting and selecting operations of the transmission are possible via asingle actuator, which may reduce the number of actuators that areapplied to the transmission, resulting in reduced price and reducedpower consumption.

For convenience in explanation and accurate definition in the appendedclaims, the terms “upper”, “lower”, “inner”, “outer”, “up”, “down”,“upper”, “lower”, “upwards”, “downwards”, “front”, “rear”, “back”,“inside”, “outside”, “inwardly”, “outwardly”, “interior”, “exterior”,“inner”, “outer”, “forwards”, and “backwards” are used to describefeatures of the exemplary embodiments with reference to the positions ofsuch features as displayed in the figures.

The foregoing descriptions of specific exemplary embodiments of thepresent invention have been presented for purposes of illustration anddescription. They are not intended to be exhaustive or to limit theinvention to the precise forms disclosed, and obviously manymodifications and variations are possible in light of the aboveteachings. The exemplary embodiments were chosen and described in orderto explain certain principles of the invention and their practicalapplication, to thereby enable others skilled in the art to make andutilize various exemplary embodiments of the present invention, as wellas various alternatives and modifications thereof. It is intended thatthe scope of the invention be defined by the Claims appended hereto andtheir equivalents.

What is claimed is:
 1. An apparatus for moving a shift rail of atransmission, the apparatus including: a control shaft provided to bemoved in a direction perpendicular to a plurality of shift rails by anactuator; a plurality of rollers protruding from one selected among acorresponding one of the shift rails and the control shaft, the rollersbeing formed on one of facing sides of the shift rail and the controlshaft; and a cam protruding in an S-shaped form from a remaining oneselected among the corresponding shift rail and the control shaft, onwhich no roller is formed, the cam being provided to selectively movethe shift rails in an axial direction by moving while coming intocontact at opposite sides thereof with the rollers depending on adistance by which the control shaft is moved, wherein the rollers arearranged side by side in a radial direction on the control shaft, andwherein the cam is formed in the S-shaped form in the radial directionon each of the shift rails, and is provided to allow the rollers tosurround and pass the cam, while the control shaft is moved.